why does bonjour make my internet lag

Everything on my computer that uses the network lags worse than using a 14k dialup. What's up with that? As soon as I killed 2 processes related to Apple/iTunes the network runs great. One of the processes was mdnsresponder.exe. Dont remember the other one. Each one was causing 10-25 connections with other apps. I'm about to treat it like a virus and purge it if it doesn't get fixed.